1. Field of the Invention
The present invention generally relates to a semiconductor device and method of forming the same, and more particularly, to a semiconductor structure including a pad opening and a fuse opening and the method of forming the same.
2. Description of the Prior Art
With the miniaturization and higher degree of integration of semiconductor devices, semiconductor devices are more vulnerable to defects or impurities arising during manufacturing process. For example, a single deficient spot in the circuitry of a semiconductor chip such as metal discontinuity, via opening or electrical characteristic shifting, may cause the whole chip fail to function.
To eliminate the problem aforesaid, it has been employed extensively in the field to incorporate fuses connecting to redundancy circuitries into the circuitry of a semiconductor chip. When a failure of the chip is defected and recognized, particular fuses may be deleted or opened to re-route circuitry along an alternate pathway, thereby repairing the chip.
Fuse structures are usually made of semiconductor materials such as poly silicon, or metals. Among them, metal fuses are more widely used for their better yield. A metal fuse may be formed integrated with a particular metal layer of the metal interconnection system, for example, one of intermediate metal layers or the last metal layer. After uppermost passivation layers are formed, pad openings are then formed to expose the pad metals for further electrical connection. Meanwhile, fuse openings are also formed to provide accesses to fuse metals.
The bottom of the fuse opening usually includes a dielectric layer covering the top surface of a fuse metals, preventing the fuse metal from being directly exposed, thereby eliminating the risk of corrosion and oxidation. However, the thickness and uniformity of the dielectric layer may interfere with the fusing process. Furthermore, during the process of forming pad openings and fuse openings, photoresist and developing solutions used in photolithography processes may be in direct contact with pad metals or fuse metals, causing residues or metal corrosion.
Accordingly, there is still a need in the field to provide optimized structures and a method of forming pad openings and fuse openings which is able to avoid the aforesaid problems.